assume cs:codesg,ds:datasg,ss:stacksg

datasg segment
  db'ibm             '
  db'dec             '
  db'dos             '
  db'vax             '
datasg ends

stacksg segment
  dw 0,0,0,0,0,0,0,0
stacksg ends

codesg segment
  start:
    mov ax,datasg
    mov ds,ax
    mov sp,16
    mov ax,datasg
    mov ds,ax
    mov bx,0

    mov cx,4
    s0: push cx
        mov si,0
        mov cx,3

        s: mov al,[bx + si]
           and al,11011111B
           mov [bx + si],al
           inc si
           loop s
        
        add bx,16
        pop cx
        loop s0

    mov ax,4C00H
    int 21H
codesg ends
end start